A telecommunication network is made of various nodes to which terminals are attached through communication controllers adapters and which are linked through multiplex links.
Due to the bursty nature of most of the data to be transported packet switching networks have been implemented to optimize the utilization of the network resources. However packet transportation implies large and variable transit delays that cannot be suffered by some real time applications. The variation of the transit delay can only be compensated by means of additional buffers at the end users, which is costly and implies delays.
On the other hand, circuit switch networks provide low constant transit delays, but lead to a bad utilization of the network links when bursty data or is to be transported through the network.
The ISDN network (Integrated Service Digital Network) described in "I" series of International Telegraph and Telephone Consulative Commitee (CCITT) Recommendations is the present approach to circuit switching and packet switching integration. However the networks using the ISDN integration technique are not optimized for the data packet traffic since the bandwidth allocated to the packet traffic is channelized.
In this type of networks which integrate the transportation of asynchronous (packet) data in dedicated packet bits and synchronous data such as voice in dedicated circuit slots there is a need to optimize the bandwith use allocated to asynchronous data type of users and to synchronous data type of users since circuit switched type of users are not always involved in a call.